The present invention relates to the field of pulse width detectors.
Although numerous pulse width detectors are present in the prior art, it is highly desirable to provide an accurate pulse width measuring circuit which produces an accurate measure of input pulse widths independent of distortions and other shifting parameters.
Where compression amplifiers comprising multiple stages coupled in tandem are employed to detect low level input pulses, the resulting output pulses have trailing edge portions which may be described as extended ripples or compression bumps. As the amplitude of the input pulses increase, more amplifier stages go into saturation so that the number of bumps and the widths of the trailing portions of the pulses increase as a function of increasing input pulse amplitudes. Hence, if one were to measure pulse widths at, for example, the halfway point between the baseline and tops of the pulses emanating from the last amplifier stage, the measurements would indicate that the pulse widths increase as a function of amplitude, thereby to produce grossly erroneous pulse width measurements. It is thus highly desirable to provide circuitry for measuring the time difference between the occurrence of the initial portion of the leading edge of the pulse and the occurrence of the initial portion of the trailing edge of the pulse corresponding to the initial degradation in amplitude at the linear portion of the first bump, so as to eliminate any measurement of the variable total degradation time of the trailing edge of the pulse. It is also important to eliminate the effects of input D.C. voltage level drifts of the pulse trains along with the effects of changes in the duty cycle of the pulse trains.